Laboratory Based Surveillance of Rabies Incidence in Ethiopian Wolf at Bale National Park, Ethiopia

Abstract

In the Bale National Park s of Ethiopia, an estimated population of 250 wolves of greater than one year age exists, according to Ethiopian Wolf Conservation Authority (EWCA) pack observation done in 2010. A new outbreak of Ethiopian Wolf was observed between July 2015 and September, 2015 at Bale Mountains National Park. A collaborative investigation between Ethiopian Public Health Institute (EPHI) and Ethiopian Wild Life Conservation Authority (EWCA) was signed to undertake laboratory based surveillance of the dead wolves. Based on the MoU, field visits were made to collect and test rabies suspected samples for the presence of Lyssavirus antigens using the direct flouresent antibody test (FAT). Five samples collected for Lyssavirus diagnostic testing, demonstrated a positive result for the presence of Lyssavirus antigen whereas four samples revealed negative results using the direct flouresent antibody test. The rabies outbreak toll reached to fifteen wolves, of which nine samples were laboratory confirmed, and other six wolves were as epi-linked to the rabies laboratory confirmation result. Suspected dog rabies cases in and around the park was also observed some months before the outbreak occurred. The prevalence of wolf rabies in July was 2/250 (0.008), whereas it was 3/250 (0.012) in August, 2015. The death report of 4/250 (0.016) Ethiopian Wolf was registered as negative dFAT result in September, 2015. The other 6/250 (0.024) death cases were not submitted for laboratory confirmation. Human exposures occurred between these two months was zero. Mass vaccination of wildlife with oral vaccine is underway intensively to prevent non outbreak packs of the animals in the park to maintain the herd immunity level of the wolf population. Further molecular detection of the evolutionary history of wolf rabies in domestic dogs in and around the park and other wild animals’ rabies reservoirs should be undertaken.